Here we have for sale a CTC Yamaha TY250/350 Mono & TY250Z TK carb Air Mixture Screw Set 46Y-14104-00
Manufactured to the exact same specification of the original Yamaha part that has now been discontinued and is no longer available.
The Air Mixture screw has been manufactured from brass and the spring has been made from stainless steel.
Shown as number 21 on the parts diagram.